1. Field of the Invention
The present invention relates to an endoscope apparatus for performing endoscopy by inserting an insertion portion which is provided with a bending portion at a distal end side, into a body cavity.
2. Description of the Related Art
In recent years, endoscopes which enable endoscopy and the like with insertion portions, which are provided with observation means at the distal end portions, inserted into subjects have been widely used in the medical field and the like.
Meanwhile, when an insertion portion is inserted into a body cavity in a complicatedly curved shape like a large intestine, for example, a skilled insertion manipulation is sometimes required.
Endoscope insertion manipulation is basically performed so that the distal end of the insertion portion is inserted toward the direction in which a body cavity (tube cavity) extends, but if a sharply curved site is present, for example, a tube cavity dark part (also simply called a dark part) to be a target position in the direction in which a tube cavity extends sometimes disappears from an observation field of view of the endoscope.
Therefore, in order to support the insertion manipulation, for example, the first conventional example of Japanese Patent Application Laid-Open Publication No. 200393328 discloses the apparatus and the method for detecting (searching for) the direction of extension of the tube cavity in which the endoscope should be inserted even when a dark part disappears, by using gradient information of brightness and darkness in an endoscopic image.
Further, the second conventional example of International Publication No. 2008/155828 stores the positional information of a dark part, and detects an insertion direction based on the positional information of the dark part which is captured in the past, if the dark part disappears.